replace

public class Replace
{

    public  static String replace(String input)
    {
        return input.replace("l", "x") ; //将hello 变为hellx
        //若input.replace("ll","a") ;则显示heao ; 若helllo则healo
        //若input.replace("l","x") ;则显示hexkxo
    }
    public static void main(String[] args)
    {
        System.out.println(replace("hello"));

    }
}